Shade - the runt of the bat colony - is determined to prove himself on the long and dangerous migration south to Hibernaculum. But he is bolder than he is strong, and when he strays from his mother and is lost in a storm, he finds himself in danger. He knows he must rejoin his colony and so begins an epic journey - from the pigeon stronghold in the city's spires to the rat kingdom in the caverns of the ground. He meets Marina, a Brightwing; Zephyr, a mysterious albino who can see into the future and the past; and Goth, a formidable giant jungle bat. But who can he trust - and where will his journey end?